Flow vector analyzer for flow bench

ABSTRACT

Apparatus and methods for airflow testing, especially for air testing of gas turbine components on an airflow test bench. Various embodiments of the present invention include the use of a measurement section downstream of the component being tested. The measurement section, in one embodiment, includes apparatus for measurement of gas properties at a plurality of spaced-apart radial locations and/or a plurality of spaced-apart circumferential locations. In another embodiment, the invention includes a method for testing a component including a comparison of gas properties measured in both forward and reverse flow directions.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 60/367,972, filed Mar. 26, 2002; and U.S.Provisional Patent Application Ser. No. 60/426,960, filed Nov. 15, 2002,both of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to improved apparatus and methods forairflow testing, and more particularly to measurement of airflowcharacteristics of a gas path component of a gas turbine engine.

BACKGROUND OF THE INVENTION

Devices such as natural gas compressors, air compressors, steamturbines, and gas turbines, include various internal components, such asvanes, stators, blades, diffusers, housings, and combustors though whichquantities of air, natural gas, steam, or combusted gas flow. It isimportant to the proper operation of these devices that these internalcomponents modify the internal flow in the correct way. Thesemodifications include changing the average properties of the flowingmedium (such as pressure, temperature, density, velocity, etc.) and/orthe profiles and gradients of these properties.

These internal components are designed to change the properties of theflowing medium within the context of the device, i.e., change theproperties in respect to internal devices either upstream or downstreamof the particular component. For example, the first stage turbine vaneof a gas turbine engine receives combusted air from a combustor andprovides the combusted air to turbine blades located downstream.

This interaction between internal components is often a function of theradial and circumferential extent of the component's flow path. Forexample, a turbine vane includes a portion of a flow path near the hub(inner most lower wall) of the vane and the outer diameter (outer mostwall) of the vane. It is typical that components such as turbine vanesprovide air in velocity and pressure gradients that change from theinner hub to the outer diameter. Further, these property gradients ofthe gas change circumferentially, i.e., the gradient closest to thetrailing edge of the vane can be different than the gradients at aposition in between adjacent trailing edges.

As vanes are manufactured, there are times when the trailing edge of thevane is bent manually. Further, it is possible that the trailing edge ofthe vane, or other geometrical aspects of the vane, is altered as aresult of long-term usage. In either of these situations, the gasproperty gradients from the exit of the vane are altered. However, theremay not be suitable test equipment for characterizing the modifiedgradients. One simple attempt to provide such information involves theuse of a protractor with a single inner foil rotatably coupled to theprotractor. As air from a tested component flows across this assembly,the angle of the airfoil changes, similar in operation to a weathervane.

What is needed is an improvement in airflow testing that improves theaccuracy with which the flow characteristics of the component aredetermined. The present invention does this in a novel and nonobviousmanner.

SUMMARY OF THE INVENTION

The present invention relates to various apparatus and methods forairflow testing of a component of a gas turbine engine.

One embodiment of the present invention includes an apparatus for flowtesting of gas through a component. The apparatus includes a test benchincluding a source of flowing gas and configured to mount the componentproximate to the aperture. The apparatus includes a measurement sectionwith an arc-shaped inner flowpath and an arc-shaped outer flowpath forreceiving therebetween the gas exiting the component. The measurementsection including a measurement device between the inner flowpath andthe outer flowpath that is being rotatable about a centerline.

Another embodiment of the present invention includes an apparatus forflow testing of gas through a component. The apparatus includes a testbench including a source of flowing gas and a housing adapted andconfigured to mount the component proximate to the aperture. Theapparatus includes a measurement section located downstream of andproximate to the aperture including at least two circumferentiallyspaced-apart measurement devices each providing a signal in response tothe flow of gas proximate thereto, and each measurement device having adifferent length in the radial direction.

Another embodiment of the present invention includes an apparatus forflow testing of gas through a component. The apparatus includes meansfor simultaneously measuring properties of the gas exiting from thecomponent at a plurality of radial locations and a plurality ofcircumferential locations, said measuring means being rotatabletransverse to the flowpath of the component.

Another embodiment of the present invention includes a method forevaluating a gasflow characteristic of a gaspath component for a gasturbine engine. The method includes mounting the component, placing ameasurement device at a first location downstream of the component;making a first measurement of a property of the gas with the measurementdevice placed at the first location, moving the measurement device to asecond location downstream of the component; and making a secondmeasurement of a property of the gas with the measurement device placedat the second location;

Another embodiment of the present invention includes a method forevaluating a gasflow characteristic of a gaspath component for a gasturbine engine. The method includes mounting the component in a firstflow direction, directing a flow of the gas into the component, making afirst measurement of a property of the gas with the component mounted inthe first flow direction, mounting the component in a second flowdirection to the support member, the second flow direction beingopposite of the first direction; and making a second measurement of aproperty of the gas with the component mounted in the second flowdirection.

Yet other aspects of the present invention will be apparent from thedescription of the preferred embodiment, the drawings, and the claims tofollow.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an airflow measurement systemaccording to one embodiment of the present invention.

FIG. 2 is a partial cutaway view of a portion of the apparatus of FIG.1.

FIG. 3 is a side elevational view of an apparatus according to oneembodiment of the present invention.

FIG. 4 is an end elevational view of the apparatus of FIG. 3 as takenalong line 4—4 of FIG. 3.

FIG. 5 is a schematic representation of an airflow measurement systemaccording to another embodiment of the present invention.

FIG. 6 is a perspective schematic representation of an airflowmeasurement device according to one embodiment of the present invention.

FIG. 7 is a schematic end view of a pair of turbine vanes providing gasflow to a pair of downstream blades.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiment illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

The present invention relates to improved apparatus and methods formeasurement of airflow through a component, such as a vane or othergaspath component of a gas turbine engine. In one embodiment, thepresent invention includes various devices and methods for directing airinto the component to be tested, and also various devices and methodsfor directing the flow of air exiting from the tested component.

In one embodiment, the present invention uses one or more air blowers toact as a source of air into a plenum chamber. Preferably, there are aplurality of devices for directing the path of the air, such as turningvanes, that accept air from the source and provide it in a predeterminedpattern to a plenum. In some embodiments, the entrance to the plenumchamber may include another flow manipulation device such as one or moresheets of perforated metal. Attached at one end of the plenum chamberand preferably along a centerline of the chamber, is a component such asan engine component for which it is desired to measure the airflowcharacteristics. Air flowing from the source through the vanes andperforated metal into the plenum chamber is presented to the inlet ofthe component in a predetermined flow pattern. Air flows from the plenumchamber through the tested component and into another flow directingmember. The flow directing member includes a plurality of flow directingdevices, such as concentric rings, flow-through cells and the like, andfinally into room ambient conditions. By controlling the conditions ofthe test, such as the speed of the air blowers, the airflow provided tothe main plenum, the pressure and temperature of the air in the mainplenum, various flow characteristics of the test component can bedetermined.

The present invention includes the discovery that placement of a flowdirecting or stabilizing member proximate to the exit of the testedcomponent improves the accuracy, reliability, and repeatability of themeasurements that pertain to the test component. Although the phenomenonmay not be completely understood, it is believed that this improvementis due, at least in part, to the stabilization of air flowing over thetested component along with a reduction in the recirculation of airexiting the tested component.

FIG. 1 schematically represents a system 20 for airflow testing of acomponent. System 20 includes a test bench 30 which includes anelectronic controller 28 for control of test bench 30 as well asmeasurement of various parameters. Located along centerline 22 of testbench 30 are a test assembly 50 and an exit flow-stabilizing member 70.As will be explained, air flows generally from ambient conditions asindicated by arrow A into test bench 30. This air is directed andcombined with other sources of air as indicated by arrows B1 and B2. Inone embodiment of the present invention, the air is further manipulatedand provided in a predetermined airflow pattern C. The air C flowsthrough the test assembly and flow stabilizing member back into ambientconditions as indicated by arrows D.

In one embodiment, test bench 30 includes an air inlet 32 for providingambient air into a flow path of the test chamber. This incoming air,indicated by arrow A, mixes with air provided form a source of air whichpreferably includes multiple air blowers 34 a and 34 b. Air blowers 34 aand 34 b provide air into turning vanes 36 a and 36 b, respectively,which direct air from these sources toward the component to be tested.Airflow B1 and airflow B2 are provided in one embodiment to a transitionduct 38 which changes its cross-sectional shape from square to round.Air exiting the round opening of duct 38 preferably flows through aplurality of perforated metal screens 40 a and 40 b into a round plenumchamber 42. Air flowing into chamber 42 flows in a predetermined patternchosen to provide accurate and repeatable testing of testing assembly50.

Referring to FIGS. 1 and 2, testing assembly 50 includes one or morecomponents 60, such as one or more vanes or other air foil shapes from agas turbine engine. However, the present invention contemplates the airflow testing of any device which is adapted and configured to providepredetermined flow characteristics such as a particular air flow at aparticular component pressure drop.

Testing assembly 50 is preferably coupled to an end 44 of chamber 42. Asbest seen in FIG. 2, test assembly 50 includes upper and lower flow pathtransition pieces 52 a and 52 b, respectively, which are mounted alongthe upper gas path walls 64 and 66, respectively, of component 60. Upperand lower flow path pieces 52 a and 52 b provide smooth andpredetermined characteristics for airflow C provided from plenum 42. Insome embodiments, transitions pieces 52 a and 52 b simulate the shapeand/or characteristics of other gaspath components of the gas turbineengine that are proximate to component 60.

Component 60 is mounted in compression between a pair of coupling plates54 a and 54 b. A screw assembly 56 maintains plates 54 a and 54 b incompression against leading and trailing edges of component 60. Acompression member (not shown) clamps a testing assembly 50 to end 44 ofplenum chamber 42 along centerline 22.

As best seen in FIG. 2, a flow-stabilizing member 70 is locatedproximate to the aft end 68 of component 60. In some embodiments of thepresent invention, there is a gap 69 between the forward most edge 71 ofmember 70 and the aft most edge 68 of component 60. In some embodimentsof the present invention and under certain flow conditions, it has beenfound that having a gap 69 of about one inch provides good repeatabilityof the measurements of the airflow characteristics of component 60. Thisadditional entrained is shown by arrows E. However, the presentinvention also contemplates those embodiments in which there is no gap69, and air flowing along the upper surface of component 60 exitsdirectly into flow stabilizing member 70.

Referring to FIGS. 2, 3, and 4, one embodiment of the present inventionincludes a flow stabilizing member 70 which includes a plurality ofconcentric rings 72, 74, 76, and 78. In one embodiment of the presentinvention, the radial distance between adjacent rings is approximatelyequal. However, the present invention contemplates any spacing betweenadjacent rings.

As best seen in FIG. 4, located between adjacent rings are convolutedmembers 73, 75, and 77. As one example, convoluted member 73 includes aplurality of folded sections 81 a and 81 b in a “saw tooth” pattern.Convoluted member 73 is formed into a round shape, and inserted betweenrings 72 and 74. Likewise, convoluted members 75 and 77 are insertedbetween respective rings. The folds 81 a and 81 b of member 73 form aplurality of cells 80 a and 80 b between rings 72 and 74. In oneembodiment of the present invention, each cell includes threesubstantially parallel walls that direct airflow therethrough in apredetermined pattern. For example, a cell 80 a is formed between a wall81 a, a wall 81 b, and a portion of ring 72, which provide aflow-through passageway for air exiting the tested component 60.Likewise, an alternate cell 80 b is formed between a wall 81 a, a wall81 b, and a portion of ring 74, which also provide a flow-throughpassageway for air exiting the tested component 60. Therefore, airexiting test component 60 flows through a plurality of three-sidedcells. It is believed that the airflow straightening provided by thesecells provides a stabilizing influence upstream to component 60, such asto either the pressure side or suction side of the air foil of vane 62,anywhere from its leading edge 63 a to its trailing edge 63 b. Referringto FIG. 2, air exiting component 60 can flow into any of a plurality ofcells 80, 82, or 84. Note that as flow stabilizing member 70 is broughtcloser to component 60 (such that gap 69 diminishes), less air iscarried through cells 84 between rings 76 and 78. Although what has beenshown and described is a three-sided cell where the three cell walls areparallel, the present invention contemplates other configurations ofmulti-walled cells, including, as non-limiting examples, square andhexagonal honeycomb cells.

Referring to FIGS. 2 and 3, an arrangement of cells and rings accordingto one embodiment of the present invention can be seen. Rings 72, 74,76, and 78 preferably have leading edges 90, which lie in a commonplane. Convoluted members 73, 75, and 77 have a leading edge 88 thatpreferably lie in a common plane. The leading edge 88 of the convolutedmembers, and therefore also the leading edge of the cells, is preferablyspaced aft of the leading edge 90 of the rings by about one-half inch.Further, the trailing edges of the convoluted edges and also thetrailing edges of the concentric rings lie in a common plane 86.However, the present invention also contemplates those embodiments inwhich none of the trailing edges of cells 80, 82, or 84 lie in a commonplane, nor do the trailing edges of the retaining rings 72, 74, 76 or78. Further, the present invention also contemplates those embodimentsin which the various leading edges of the rings and convoluted membersare not offset from one another. Additionally, the present inventioncontemplates those embodiments in which none of the leading edges of theconcentric or the convoluted members share a common plane.

In one embodiment of the present invention, there is an apparatus forairflow testing of a component. The apparatus includes a test benchincluding a source of air, a plenum, and at least one member fordirecting air from the source into said plenum. The apparatus includes acomponent receiving air from the plenum, the air flowing through thecomponent. The apparatus includes a flow stabilizing member locatedproximate to the component and receiving air from the component, theflow stabilizing member including a plurality of open cells, each cellhaving a plurality of parallel walls for passage of a portion of the airfrom the plenum therebetween.

In another embodiment of the present invention, there is an apparatuswith a source of air. The apparatus includes a component adapted andconfigured for redirection of air passing therethrough. The apparatusincludes a means for directing air from the source to the component andmeans for redirecting air received from the component, the redirectingmeans including a plurality of multiwalled, flow-through passages forreceiving and redirecting air exiting from the component.

In still another embodiment of the present invention, there is a methodfor testing the airflow characteristics of a gaspath component for a gasturbine engine. The method includes providing a source of air, a plenumchamber with two ends, a gas turbine gaspath component to be tested, anda plurality of cells defining flow-through passageways. The methodincludes directing the air from the source into one end of the plenumchamber, mounting the component at another end of the chamber, flowingthe air through the chamber to the component, flowing the air throughthe component, and directing the air exiting the component through thepassageways.

Yet another embodiment of the present invention concerns systems,apparatus, and methods for measurement of airflow through a component,such as a vane or other gas path component of a gas turbine engine. Inone embodiment, the present invention includes various devices andmethods for directing air into the component to be tested, and alsovarious devices and methods for measuring various characteristics of thegas exiting from the tested component.

In one embodiment, the present invention uses one or more of the variousair blowers, plenum chambers, turning vanes, air conditioning equipment,and control devices described previously herein. By controlling theconditions of the airflow test, such as the speed of the blowers, thedirection of the airflow, and/or the pressure and temperature of theair, various flow characteristics of the test component can bedetermined.

Some embodiments of the present invention have been developed from theunderstanding that the characteristics of gas flowing through an airflowcomponent such as a turbine nozzle depend upon a variety ofcharacteristics of the nozzle.

FIG. 7 is a schematic representation of gas flowing between a pair ofturbine vanes 1001, also known as a turbine nozzle, and onto the blades1002 of a rotating turbine wheel. The air exiting the turbine vaneschange both velocity and direction. The velocity of the air increasesbecause the distance between the turbine vanes acts as a convergingnozzle, and also since the gas flow is subsonic. Further, the vanes havea curved shape that changes the direction of air such that the airexiting the trailing edge of the turbine nozzle is directed at the highpressure side of the turbine blades in the next stage of the engine.

The flow characteristics of adjacent rows of vanes and blades arecarefully matched. However, the actual flow characteristics of a set ofturbine vanes can vary considerably from the desired flowcharacteristics for various reasons, including manufacturingdifficulties, inaccurate inspection and measurement techniques, wear anderosion during operation, and inaccurate or inconsistent repairtechniques. For any of these reasons the actual throat of a pair ofadjacent vanes can vary from desired values. Further, thecharacteristics of the vane trailing edge, including length, thickness,and angle can vary.

Compounding these problems are inaccuracies in the measurement of flowcharacteristics in a test rig. It is desirable to determine vane flowcharacteristics on test rig, prior to installation in an engine. In someapplications, the vanes may be altered during airflow testing so as toachieve a desired airflow characteristic. However, it has been observedthat altering a set of vanes to achieve a flow characteristic asmeasured on a test bench is not necessarily a good predictor of theperformance of those same vanes when installed in an engine. Because ofthese test uncertainties, it is possible that a particular set of vanesmay be repeatedly bench tested, altered, and engine tested until asuccessful engine test is performed.

It is believed that one reason for the discrepancy between bench testingand engine testing, and further between different bench tests, isbecause of the angle and relative turbulence of the air exiting from thetrailing edge of the vane. For example, in vanes that have thicktrailing edges as a result of repair procedures, there can be excessiveturbulence as the air leaves the vane airfoil shape. Further, thetrailing edge of the vane may be bent at the wrong angle, either as aresult of manufacturing difficulties, handling, or salvage and repairprocedures, such that the air exits at the wrong angle. Further, it ispossible that flow separation will occur along the low pressure side ofthe vane if the trailing edge has been excessively bent. In addition, itis possible that the vane throat and/or trailing edge configuration mayvary radially. For example, if the trailing edge of a vane has beenmanually bent; then it is possible that the greatest amount of bendingoccurred at a point midway between the inner radius hub and the outerradius shroud of the vane. Therefore, the airflow exiting at a pointmidway along the span of the vane can have a different exit angle thanthe airflow exiting near the hub of the vane.

The present invention includes apparatus and methods for more accuratelydetermining the characteristics of airflow exiting a set of vanes. Inone embodiment, the present invention includes a measurement sectionpreferably located downstream of the airflow component being tested.This measurement section includes one or more devices or sensors whichprovide a signal corresponding to the airflow flowing in the vicinity ofthe device or sensor. Further, these sensors may be positioned atvarious radial locations so as to quantify flow characteristics of theair exiting the vanes at the corresponding radial distance.

In yet another embodiment of the present invention, the component to betested is tested with air flowing in both the forward 1010 and reverse1020 directions. For example, a first test is performed with air flowingthrough the tested component in the typical fashion (such as that shownin FIG. 7 for the turbine nozzle). From this first test, a flowcharacteristic, such as the vane area, vane angle, or other parameter isdetermined. Following this first test, the same component is mounted forreverse flow, preferably using the same flow bench as the first test,although some different adapting fixtures may be necessary. In thesecond test, air is flowed through the component in the directionopposite to the typical and expected direction of flow, as indicated bythe opposite direction arrow 1020 of FIG. 7. Following this second test,one or more flow parameters are determined, which can be the same as theflow parameter determined during the first test, or a differentparameter altogether. The method preferably includes comparing the firstflow characteristic to the second flow characteristic in mathematicalfashion, such as by cross plotting, forming a ratio, a multiple, adifference, or other mathematical relationship. This calculatedparameter is then used to determine whether of not the tested airflowcomponent is acceptable or not.

The use of a one-hundred series prefix (1XX) with an element number (XX)refers to an element that is the same an the non-prefixed element (XX)previously described or depicted, except for the differences which aredescribed or depicted hereafter.

FIG. 5 schematically represents a system 120 for airflow testing of acomponent, such as one or more arc-shaped turbine vane segments. Airflows generally from ambient conditions as indicated by arrow A intotest bench 130, and is directed, combined, manipulated, and flows backto ambient as indicated by arrows B, C, and D.

In one embodiment, test bench 130 includes a testing assembly 150 thatincludes one or more components 160, such as one or more turbine vanes,compressor stators, diffuser stators, other airfoil shaped, or otherairflow components, including but not limited to those from a gasturbine engine. However, the present invention contemplates the airflowtesting of any device which is adapted and configured to providepredetermined flow characteristics such as a particular airflow at aparticular component pressure drop, a particular air exit angle, aparticular air velocity, air temperature, and/or combinations of thesecharacteristics, including variations in these characteristics as afunction of radial, angular, and axial location.

Component 160 (not shown) is mounted within testing assembly 150 in anymanner. Preferably, the manner of mounting component 160 provides forthe placement of a closely located measurement section 191 adjacent anddownstream of component 160. In some embodiments of the presentinvention, component 160 is mounted with interstage seals, manifolds,brackets, and/or shrouds 170 which are also adjacent the test component160 when it is installed in its typical operating apparatus. However,the present invention also contemplates those embodiments in whichspecially designed flow straighteners, mixers, seals, airflow paths, andother apparatus are installed upstream and/or downstream of testcomponent 160.

Referring to FIG. 5, system 120 includes a measurement section 191preferably located downstream of test component 160. In one embodiment,measurement section 191 includes an outer shroud 192 for generallycontrolling the flow of air exiting from test component 160. Measurementsection 191 further includes a measurement assembly 195 which ispreferably rotatable about 360 degrees. In one embodiment, rotation ofmeasurement assembly 195 is provided by an electric motor 105 coupled tomeasurement assembly 195 by a coupling 106. In some embodiments of thepresent invention, coupling 106 is a viscoelastic coupling incorporatingdampening. In yet other embodiments of the present invention, coupling106 is a solid coupling. Motor 105 is housed within a motor shroud 111,shroud 111 providing the inner walls of the flow path for air flowingthrough measurement section 191. In some embodiments, the flow annulusbetween inner shroud 111 and outer shroud 192 includes one or more vanesfor changing the direction of air exiting measurement section 191.

In one embodiment of the present invention, airflow exiting from testcomponent 160 passes around one or more airflow devices, with one ormore of these devices incorporating a sensor. FIG. 6 is a schematicrepresentation of a measurement section 195 according to one embodimentof the present invention. Measurement section 195 includes a wheel 196with three airfoil-shaped measurement devices 197, 198, and 199. Eachmeasurement device 197, 198, and 199 extends a different radial distancefrom the outer surface (inner hub) of wheel 196. As installed in system120, measurement device 197 extends across the entire radial length ofthe flow path, which can coincide with the radial length of the turbinevane being tested. Measurement device 198 extends across only a portionof the span from the flow path inner diameter to the flow path outerdiameter. Measurement device 199 also extends across only a portion ofthe distance from the flow path inner diameter to the flow path outerdiameter and preferably is of a shorter radial length than measurementdevice 198. Although what has been described and depicted aremeasurement devices 197, 198, and 199 that are airfoil shaped like aturbine blade, the present invention also contemplates those embodimentsin which devices 197, 198, and 199 are different length rods, plates, orother shapes. Further, although the present invention shows thesemeasurement devices places adjacent one another, the present inventionalso contemplates those embodiments in which the devices are spacedapart from each other along the circumference of wheel 196. Further, thepresent invention contemplates those embodiments in which each of themeasurement devices has the same radial extent from hub to outerdiameter.

As best seen in FIG. 6, each measurement device 197, 198, and 199preferably includes a corresponding sensor 101, 102, and 103,respectively. In one embodiment, sensors 101, 102, and 103 are straingauges which measure the bending strain of the measurement device towhich it is attached. However, the present invention also contemplatesthose embodiments in which the measurement devices are accelerometers,hot-wire anemometers, pressure taps with corresponding pressuretransducers, or any other sensor which can detect the response ofmeasurement device 197, 198, or 199 to the gas flow exiting fromcomponent 160, or which can respond directly to the gas flow itself. Asone example, measurement assembly 195 may include one or moremeasurement devices which include an array of pressure taps, arranged,for example, around and along the leading edge of the measurementdevice. Further, the sensor maybe mounted directly on the surface of themeasurement device, as can be the case with a strain gauge. As anotherexample, the device may be hollow and incorporating an accelerometerlocated internally. Further, the measurement device can include one ormore flow passages with an entrance on one surface of the measurementdevice (such as the leading edge), and an exit on another surface of themeasurement device (such as the trailing edge). Located within this flowpassageway can be a sensor such as a hot-wire anemometer. In yet antherembodiment of the present invention, the measurement device includes acontrolled source of heat and a thermocouple. The signal from thethermal couple changes in accordance with the control of the flow ofheat and also with the amount of air flowing through the passageway.

During operation, the system operator uses motor 105 to rotatemeasurement assembly 195 through a 360 degree arc, or in someembodiments, a lesser arc. In so doing, the measurement devices 197,198, and 199 react to the impingement of airflow received from theupstream test component 160. For assembly 195 depicted in FIG. 6,measurement device 197 exhibits a response that is influenced by airexiting from a portion of the test component at all radial locations. Incontrast, measurement device 199 is more heavily influenced by airexiting from a portion of the hub of component 160, and is lessinfluenced by air exiting near the outer diameter of component 160.Measurement device 198 is influenced in a manner intermediate of devices197 and 199.

An angular resolver 108 is coupled to the shaft of motor 105, andprovides an electrical signal corresponding to the angular location ofmeasurement devices 197, 198, and 199. The signals from the sensors 101,102, and 103 are provided to a system data controller (not shown) which,combined with the signal from resolver 108, can plot the circumferentialvariation of the sensor as it traverses completely around the flow pathof the test component 160.

By cross plotting the angular orientation of test assembly 195 with thereading from the sensors 101, 102, and 103, the resulting circular plotcan indicate areas of low strain (or other measured parameter), whichcorrespond to areas of low airflow. Further, the width of the variouspeaks and valleys of the circular plot correspond to variouscharacteristics of the tested component, including width of the throatand exit angle from the component trailing edge. In addition, comparisonof the circular plots from sensor 101 and 103 indicate radialdifferences in air flowing between a pair of particular vanes.

In yet another embodiment of the present invention, measurement section191 includes a load cell 107 located between motor 105 and rotatingmeasurement assembly 195. As air strikes one or more measurement device,a torque results on the shaft connecting motor 105 and wheel 196. Thistorque can be cross plotted with the angular position measured byresolver 108 to produce a circular plot showing torque as a function ofangular position, which is indicative of airflow and/or flow angle froma corresponding position of the test component 160.

In yet another embodiment of the present invention, any of theheretofore described tests and measurements are performed with component160 installed to receive air in a typical fashion, and then repeatedwith component 160 mounted in reverse manner so as to receive flow in areverse direction. The present invention contemplates embodiments forforward and reverse airflow testing both with and without a measurementsection. For those embodiments not including a measurement section 191,it is possible to determine overall flow characteristics of the testcomponent. For example, it is expected that the calculated flow area fora turbine nozzle in the reverse direction, divided by the flow area forthe same turbine nozzle in the forward direction can be a ratio lessthan one. Based on design parameters of the particular gas turbineengine, and also engine test measurements, acceptable numbers for thisarea ratio can be established. For those applications in which acompressor diffuser is the test component, it is expected that theforward-measured area divided by the reverse-flow measured area can be aratio less than one.

For those embodiments including a measurement section 191, the circularplots for forward-flowing air and reverse-flowing air can be compared.Based on the comparison of forward and reverse flowing installations,ranges of acceptable values can be established for the tested component.Note that the present invention contemplates any type of datacomparison; any data taken from the forward-flowing test can be comparedto the data taken from the reverse-flowing test, including but notlimited to logarithmic comparisons, frequency comparison, ratios,differences, and temperature and pressure comparisons.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. An apparatus for flow testing of gas through an arc-shaped component, comprising: a test bench including a source of flowing gas and a housing defining a plenum chamber and an aperture for flowing of the gas into the component, said housing being adapted and configured to mount the component proximate to the aperture; and a measurement section located downstream of and proximate to the aperture, said measurement section including an arc-shaped inner flowpath and an arc-shaped outer flowpath for receiving therebetween the gas exiting the component, said measurement section including a measurement device between the inner flowpath and the outer flowpath, said measurement device providing a signal in response to the flow of gas proximate thereto, said measurement device being rotatable about the centerline of the arc of the component.
 2. The apparatus of claim 1 wherein said measurement section includes a platform with a plurality of measurement devices each located between the inner flowpath and the outer flowpath, said platform being rotatable about the centerline.
 3. The apparatus of claim 1 wherein said measurement section includes a plurality of measurement devices, each measurement device has a length in the radial direction between the inner flowpath and the outer flowpath, and each length is different.
 4. The apparatus of claim 3 wherein each measurement device includes a sensor, and the sensor is one of a strain gage, pressure transducer, accelerometer, anemometer including a wire, or piezoresistive element.
 5. The apparatus of claim 4 wherein at least one of said measurement devices is in the shape of an airfoil.
 6. The apparatus of claim 1 wherein said apparatus includes as the component an arc-shaped vane for a gas turbine engine.
 7. The apparatus of claim 6 wherein said measurement device includes a sensor for measuring the angular position of said measurement device relative to the component.
 8. The apparatus of claim 1 which further comprises a sensor producing a signal corresponding to the torque imparted by the airflow onto said measurement device.
 9. The apparatus of claim 1 wherein said measurement device is in the shape of an airfoil.
 10. The apparatus of claim 1 wherein said measurement device is in the shape of a plate.
 11. The apparatus of claim 1 wherein said measurement device is in the shape of a rod.
 12. The apparatus of claim 1 wherein said measurement section includes a plurality of measurement devices.
 13. The apparatus of claim 12 wherein each said measurement device includes a sensor producing a signal corresponding to the torque imparted by the airflow onto said measurement device.
 14. The apparatus of claim 13 wherein at least one of said measurement devices is in the shape of an airfoil.
 15. The apparatus of claim 1 wherein said housing is adapted and configured for mounting a vane for a gas turbine engine.
 16. The apparatus of claim 15 wherein the gas flowing through said measurement section exits said measurement section by flowing into ambient conditions.
 17. The apparatus of claim 1 wherein the gas flowing through said measurement section exits said measurement section by flowing into ambient conditions.
 18. An apparatus for flow testing of gas through a component, comprising: a test bench including a source of flowing gas and a housing defining a plenum chamber and an aperture for flowing of the gas into the component, said housing being adapted and configured to mount the component proximate to the aperture; and a measurement section located downstream of and proximate to the aperture, said measurement section including an inner flowpath and an outer flowpath for receiving therebetween the gas exiting the component, said measurement section including at least two circumferentially spaced-apart measurement devices each located between the inner flowpath and the outer flowpath, each said measurement device providing a signal in response to the flow of gas proximate thereto, each measurement device having a length in the radial direction between the inner flowpath and the outer flowpath, and each length being different.
 19. The apparatus of claim 18 wherein each said measurement device is in the shape of an airfoil.
 20. The apparatus of claim 18 wherein each said measurement device is in the shape of a plate.
 21. The apparatus of claim 18 wherein each said measurement device is in the shape of a rod.
 22. The apparatus of claim 18 wherein the component is arc-shaped and said measurement section is rotatable across the arc.
 23. The apparatus of claim 22 wherein said measurement section includes a sensor for measuring the angular position of said measurement device relative to the component.
 24. The apparatus of claim 18 wherein at least one of said measurement devices includes a sensor, and the sensor is one of a strain gage, pressure transducer, accelerometer, anemometer including a wire, or piezoresistive element.
 25. The apparatus of claim 18 wherein said housing is adapted and configured for mounting a vane for a gas turbine engine.
 26. The apparatus of claim 25 wherein the gas flowing through said measurement section exits said measurement section by flowing into ambient conditions.
 27. The apparatus of claim 18 wherein the gas flowing through said measurement section exits said measurement section by flowing into ambient conditions.
 28. The apparatus of claim 18 which further comprises a sensor producing a signal corresponding to the torque imparted by the airflow onto said measurement device.
 29. An apparatus for flow testing of gas through a component, comprising: a test bench including a source of flowing gas and a housing defining a plenum chamber and an aperture for flowing of the gas into the component, said housing being adapted and configured to mount the component proximate to the aperture; and means for simultaneously measuring properties of the gas exiting from the component at a plurality of radial locations and a plurality of circumferential locations, said measuring means being rotatable transverse to the flowpath of the component.
 30. The apparatus of claim 29 wherein said measuring means includes a plurality of devices each adapted and configured to bend in response to the gas flowing out of the component and around the device.
 31. The apparatus of claim 30 wherein at least one of said measurement devices is in the shape of an airfoil.
 32. The apparatus of claim 30 wherein at least one of said measurement devices is in the shape of a plate.
 33. The apparatus of claim 30 wherein at least one of said measurement devices is in the shape of a rod.
 34. The apparatus of claim 30 wherein said measuring means includes a sensor producing a signal corresponding to the torque imparted by the airflow onto said measuring means.
 35. The apparatus of claim 29 wherein said housing is adapted and configured for mounting a vane for a gas turbine engine.
 36. The apparatus of claim 35 wherein the gas flowing through said measuring means exits said measuring means by flowing into ambient conditions.
 37. The apparatus of claim 29 wherein the gas flowing through said measuring means exits said measuring means by flowing into ambient conditions.
 38. The apparatus of claim 29 wherein the component is arc-shaped and said measurement section is rotatable across the arc.
 39. The apparatus of claim 38 which further comprises a sensor for measuring the angular position of said measuring means relative to the component.
 40. The apparatus of claim 29 wherein said measuring means includes a sensor, and the sensor is one of a strain gage, pressure transducer, accelerometer, anemometer including a wire, or piezoresistive element. 